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Chimney Damper

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What Is A Chimney Damper And Why Is It So Important?

Chimneys are essentially hollow passages through which hot air from inside your room can escape. It not only makes your fireplace inefficient but also increases your energy bills by a significant margin.

To tackle this issue, a chimney damper was invented. A damper is essentially a door inside or at the top of a chimney flue that is used to regulate the chimney flow.

Throughout the article, we’ll not only discuss why a chimney damper is important but also discuss its various types, how to operate them, various issues with dampers, and their solutions among other things.

But before all that, let’s discuss the basics.

What Is a Chimney Damper?

A chimney damper is a door or a lid that can be opened or closed manually. Located, traditionally, at the base of the chimney (inside the chimney flue), a chimney damper helps control the airflow inside the chimney.

Do All Fireplaces Have a Damper and Is It Necessary?

While all fireplaces don’t need a damper, having one installed can be beneficial. A chimney without a damper allows for warmer air in the room to escape. Since the heat generated inside is lost, more combustion and time are required to heat the room, resulting in higher energy bills. Also, even when the chimney is not in use, air from outside can get inside and cool down the interior in winters.

Having a chimney damper can stop the outside cold air from entering and keep the warmer air inside, thus keeping the room warmer.

However, there’s a chance that you might not need a damper. For example, modern wood-burning stoves have a perfectly sized flue that can regulate airflow while the fire is burning. And because the front door panel is closed, there is no issue of drafts when the fire is not burning. 

Importance of a Fireplace Damper

Initially, chimneys were hollow passages to let the smoke outside. However, it was realized overtime that such a simplistic design had several issues. Essentially acting as a door of a chimney flue, a chimney damper was invented to solve many of these issues.

Here are some of the most significant use cases of a chimney damper:

  • When your fireplace is lit with mellow fire and you want to increase its intensity, you can do that by adjusting your chimney damper accordingly. Since air (oxygen) is essential for the process of combustion, more air (oxygen) means better combustion and, consequently, a stronger fire. On the other hand, less air (oxygen) means there is not enough oxygen for proper combustion and a lighter fire is produced. Therefore, by adjusting your damper position (opening it more or less) you can control the airflow inside your chimney and, by that, control the intensity of the fire in your fireplace.
  • Another important job that your damper does is that when your fire is burning, it lets the smoke and Carbon Monoxide out through the chimney flue.
  • Without a damper, outside cold air can enter your house while the warmer air, inside, can espace; decreasing the temperature inside. Therefore, having a damper will not only help keep your room warmer but also save you a lot in energy bills.

What Are Types of Chimney Dampers?

Wood Stove Damper

The main function of a wood stove damper is to regulate the exhaust flow of your chimney. They allow you to adjust how much outside airflow gets inside which helps in regulating the fire in your fireplace.

Throat Damper

Traditionally, dampers were located at the throat of the chimney, directly above the fireplace. These dampers, known as throat dampers, are commonly found in masonry systems. Throat dampers are positioned as such to keep them hidden (for aesthetic purposes) but also within enough reach to operate them directly from within a fireplace.

How to Open or Close a Throat Damper?

A throat damper usually consists of a (steel or cast iron) handle and a metal plate that acts as a door connecting your chimney flue to the firebox.

Throat dampers can be further divided into three types depending upon how they operate. Let’s see how you can open and close each of them:

Rotary: Instead of a handle, a rotary damper has a screw-like key that can be accessed from your fireplace. Simply rotate the key left to open the damper and right to close it.

Poker: A poker damper has a curved handle that consists of grooves that help keep it in place. To open the damper, simply push the handle outwards to free it and move it to its desired position. Then pull the handle until you hear a thud (that means the handle has been locked in its place.)

Pivot: A variation of the poker damper, the pivot damper has a long handle with joints. You can open and close a pivot damper similar to a poker damper, the only difference is that you move the handle forward or backward with the notches.

If you’re still confused, here’s a video representation of how to operate various types of throat dampers.

Problems With Throat Dampers

Since throat dampers are located just above the fireplace, the heat from the fire can eventually wrap them, thus, rendering them useless. Throat dampers, made from metal, can also be damaged by moisture and rust, which can ultimately worsen their performance.

Top Sealing Damper

Instead of being inside the chimney, you’ll find a top sealing damper on top of the chimney. A top sealing damper, also called a chimney cap damper or a top-mounted damper usually has a spring-loaded door located inside your chimney cap. It creates a tighter seal than a throat damper because of the presence of a gasket.

Apart from controlling the airflow inside your chimney flue, a top sealing damper (when open) also prevents small animals, birds, dust, and moisture from entering the chimney.

Since a top-sealing damper provides a better seal, it’s much more energy-efficient and is better at keeping warm air inside.

How to Open or Close a Top Sealing Damper?

The seal of a top-sealing damper is connected to a cable (made from stainless steel) that runs down your chimney and can be easily accessed from your firebox. To open a top-sealing damper, you let the chain loose to let it move upwards. And to close it, simply pull the chain down and stick it into the notch to keep it in place.

Here’s a video representation of how to operate a top-sealing damper.

Types of Top Sealing Dampers

A top-sealing damper can be further categorized into the following two types:

Lyemance Damper: A type of top-sealing damper that, when opened, swings down. The lyemance damper uses a cable and handles to shut or open the damper. It’s not a great choice if you live in snowy areas because a lyemance damper is known to freeze shut. Since the surface of the damper is flat, the snow is collected atop, making it difficult to open. However, there’s a kick inside, that helps break open the frozen damper door.

Loc-Top Damper: A Loc-Top damper is more common and pops open because of a spring assembly. It also utilizes a cable and handle for opening or closing. While it’s good for snowy areas, the spring assembly of a loc-top damper can malfunction and remain closed. The spring assembly can, over time, lose its elasticity and malfunction. Creosote can also gather at the spring joint rendering the spring assembly and the damper useless.

When to Open and Close Your Chimney Damper?

A chimney when not in use should be closed.

Some people have the wrong notion of how a chimney works. They believe, that since a chimney pulls out warm air in the winters, it would do the same in summers; keeping your house cold in winters. However, that’s not how it works.

An open chimney essentially acts as a window. It pulls out whatever air is inside; be it hot or cold. Therefore, it is important to keep your chimney damper closed in summer especially if you’ve got air conditioning on. Keeping the damper open would allow the cooler air to escape from the chimney top, thus, warming your interior.

Even in winters, when the fire is not burning, your chimney damper should remain closed. This will prevent the inside warm air from escaping.

Close the damper if there’s a chance of rain or storm. An open damper would allow debris and water to enter your house through the chimney. Even if you’ve got a chimney cap, there’s a chance some of the rainwater and debris would enter. Not only is moisture and dust detrimental to your chimney but they can also make it difficult to light a fire because of moisture in the fireplace.

Precaution

However, before closing your damper, make sure that there are no burning (glowing) coals by stirring the ash inside the fireplace. If the damper is closed while the coals are still burning, the ongoing combustion will release Carbon Monoxide (CO). Since the CO gas has no place to go, it’ll remain inside the room. CO gas is dangerous and can prove to be lethal.

Therefore, always make sure all coals are dead and that the combustion has ended before closing your chimney damper.

If you’re in a hurry and the coals are still glowing, leave the damper partially open. This will not only block the drafts but also let the harmful exhaust gasses escape.

How to Tell if Your Fireplace Damper Is Open or Closed?

If you start a fire and your fireplace damper is closed, in no time your room will fill with smoke. The fire will also struggle to stay lit because there will not be enough air to supply oxygen for proper combustion.

Therefore, always make sure your fireplace damper is open before igniting a fire. But how do you ensure that your fireplace damper is open?

There are a few ways of knowing whether your damper is open or close, let’s discuss them one by one:

Visual Inspection

One of the best ways to check whether your chimney damper is open or closed is to see it by sticking your head inside the fireplace and looking up.

If you’ve got a throat damper, your vision will be blocked in case of a closed damper. You can also touch the metal plate of the damper. However, if your damper is open, you will see the inside of your chimney flue.

In the case of a top-sealing damper, if you can see sunlight at the top of your chimney that means your damper is open. If you can’t, that means your damper is closed.

Check the Draft

An open fireplace damper will allow airflow inside the chimney flue. If you place your hand inside your fireplace and feel a draft, that probably means your fireplace damper is open. However, that’s not always the case.

Sometimes, the draft you’re feeling is not because your damper is open but because of air stored inside the chimney liner (flue); especially if you have a top-sealing damper installed.

Check the Damper Controls

We’ve already discussed how one can open and close different types of chimney dampers. Knowing that will allow you to know whether your damper is open or closed simply by checking the state of the controls.

In case you forgot, you can do a visual inspection.

Check for Outside Sounds

It’s amazing how a hollow chimney flue can amplify sounds of outside air, traffic, etc. If you’re hearing sounds from outside, you’ve got an open damper. If not, your damper system is closed.

It’s better to use multiple methods to confirm whether your damper is open or closed.

Chimney Damper Repair and Maintenance

If you’re thinking you’re all good after installing a new chimney damper, then think again. Dampers, if not properly maintained, can get damaged or broken. A broken damper can lead to various issues, as listed below:

Chimney Damper Issues

Blockage

When dirt starts to accumulate around the hinges and valves of your fireplace damper, it gets stuck. Once that happens, you won’t be able to open or close your damper. If your damper gets stuck, don’t light a fire as it will result in dangerous exhaust gasses (e.g. CO, smoke, etc.) leaking inside your room.

Outside Drafts

If you’ve got a damaged silicone rubber seal or your damper system has malfunctioned and is stuck in an open position, you’ll notice cold air drafts from outside entering your room. This can decrease the efficiency of your fireplace and increase your energy bills drastically.

Wrongly Placed Plate

If your damper plate is not placed in its proper position, the trajectory of the exhaust gasses from the fire will be altered. It can result in smoke and other dangerous gasses turning back into your room.

Failure to Open or Close

If your chimney damper system is broken or malfunctioned, it’ll be difficult to open or close. If you can properly open your damper, smoke and other harmful gasses and toxins from the combustion won’t be exhausted properly. It can pose a serious threat to the health of your family.

And while an open damper is not a serious threat, it can drastically increase your energy bills as most of the heat inside your house will escape through the open chimney.

Throat Damper Repair

If you notice any of the above issues, don’t use your fireplace before fixing them. While you can fix some of the chimney damper issues, others require expertise and are better left to professionals.

Let’s take a look at some of the easier fixes:

Clean the Damper

Sometimes, all you need is to clean your fireplace damper to have it up and running to its maximum potential. But before you go about cleaning your damper and its surrounding area, remove all the dust, ash, and unused logs from your fireplace.

Once done, get inside your fireplace and find your fireplace damper. Use a steel brush to clean it (you can also use a whisk broom.)

If you find that your chimney damper is clogged, apply penetrating oil to its hinge and handle. This will most probably open the damper. Once opened, remove all the dust and debris on top of it and your damper will be as good as new.

Remove the Damper Plate

There are times when just superficial cleaning of the damper won’t be enough. If that’s the case, it’s time to remove your fireplace damper plate. Luckily enough, it’s not as tough of a job as one might think.

If you look up from inside your fireplace, you’ll find a rod fixed into the chimney with a bolt. Once you twist open the bolt the damper plate will come down (for certain models, you might need to twist it a bit to bring it down.)

Once you’ve removed the damper plate, clean the frame on which the damper plate is placed. After that, clean the damper plate and ultimately the rod. You should also look out for corrosion.

If you remove the damper plate and it’s wrapped or if you find cracks in it, you’ll need to get a new damper plate.

Most chimney dampers have silicone seals to block the cold drafts from outside. If you have a silicone seal, check to see if it’s fine. If it’s broken, replace it.

Reinstalling the Damper Plate

Once you’ve thoroughly cleaned the damper frame, damper plate, rod, and the surrounding area, place back the damper plate. However, make sure that your damper plate is perfectly aligned. Once ensured, make sure that the damper is working properly by opening and closing it. If it is, place the damper rod and secure the nut tightly.

Top Sealing Damper Repair

It’s harder to fix a malfunctioned top sealing damper because of its position. To clean a top sealing damper you’ll have to climb up your rooftop which can be difficult as well as dangerous.

Once you get to the damper, start by removing the dust particles from the seal. After that, add lubricant to the moving parts of the damper. Move the damper several times so that the parts that were stuck can loosen up.

Also, if you can, have someone at the bottom to open and close the damper through the chain to ensure it is working properly.

Chimney Damper Replacement Cost

If your chimney damper is wrapped, has cracks, or is simply broken, it’s important to get a new one installed for the optimal functioning of your chimney. To get an idea of the price of getting a chimney damper replacement, here’s a detailed table:

Low-Cost EstimateHigh-Cost Estimate
Throat damper (cast iron)150 USD250 USD
Top sealing damper200 USD300 USD
Damper plate50 USD150 USD
Professional damper repair100 USD225 USD
Professional Installation (excluding damper cost)200 USD400 USD



The Takeaway

A chimney damper is an important part of your chimney. While not all chimneys require a damper, having one can be beneficial in most cases. Not only does it help regulate your fire but it also helps keep your energy bills low by not letting the warmer air escape.

It’s important to have your damper closed when your fireplace is not in use. It will keep the warmer air inside. However, when your fireplace is in use, your damper should be open to let the smoke and other harmful gasses out through your chimney.

Rust and debris can build up and block the damper making it difficult to open or close. Therefore, regular maintenance of your chimney damper is crucial to keep it functioning properly.

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